Peter Pan disk

A Peter Pan disk is a circumstellar disk around a star or brown dwarf that appears to have retained enough gas to form a gas giant planet for much longer than the typically assumed gas dispersal timescale of approximately 5 million years. Several examples of such disks have been observed to orbit stars with spectral types of M or later. The presence of gas around these disks has generally been inferred from the total amount of radiation emitted from the disk at infrared wavelengths, and/or spectroscopic signatures of hydrogen accreting onto the star. To fit one specific definition of a Peter Pan disk, the source needs to have an infrared "color" of , an age of >20 Myr and spectroscopic evidence of accretion.[1][2]

In 2016 volunteers of the Disk Detective project discovered J080822.18-644357.3. This low-mass star showed signs of youth, for example a strong infrared excess and active accretion of gaseous material. It is part of the 45+11
−7 Myr old Carina young moving group, older than expected for these characteristics of an M-dwarf.[3][4] Other stars and brown dwarfs were discovered to be similar to AWI0005x3s, with signs of youth while being in an older moving group.[4][2] Together with J080822.18-644357.3, these older low-mass accretors in nearby moving groups have been called Peter Pan disks in one scientific paper published in early 2020[5][2], but this term has not been widely adopted as a name for this class of circumstellar disks and it has not been used in scientific publications by other independent research groups.

Name

Peter Pan disks are named after the main character Peter Pan in the play and book Peter Pan, or The Boy Who Wouldn’t Grow Up, written by J.M. Barrie in 1904. The Peter Pan disks have a young appearance, while being old in years. In other words: The Peter Pan disks "refuse to grow up", a feature they share with the lost boys in Peter Pan.[2][1]

Characteristics

The known Peter Pan disks have the H-alpha spectroscopic line as a sign of accretion. WISE J080822.18-644357.3 shows variations in the Paschen-β and Brackett-γ lines, which is a clear sign of accretion.[1][2] It was also identified as lithium-rich, which is a sign of youth.[4]

WISE J080822.18-644357.3 shows variations in the light curve from CTIO, which could be disk material blocking light from the star. The source also showed a strong flare.[1][2] WISE J080822.18-644357.3 shows three distinct disk components: A "hot" inner disk with a temperature of 1100 K (827 °C or 1520 °F), located at 0.0056 au. A "warm" outer disk with a temperature of 240 K (-33 °C or -28 °F), located at 0.115 au.[4] A "cold" outer disk with a temperature of 20 K (-253 °C or -424 °F), located at <16 au.[6]

2MASS J05010082-4337102 showed a flare in a TESS light curve and periodic variations, which could be due to starspots. The system is inclined to our line of sight by ~38°, enough to not expect any disk material to move in front of the star.[1][2]

WISEAJ044634.16-262756.1 and WISEA J094900.65-713803.1 are both apparent visual double in Gaia data.[2]

2MASS J02265658-5327032 is a candidate brown dwarf with a Peter Pan disk.[2]

Known Peter Pan disks
Artist's Impression of AWI0005x3s (WISE J080822.18-644357.3)

The prototype Peter Pan disk is WISE J080822.18-644357.3.[2] It was discovered by the NASA-led citizen science project Disk Detective.[7]

Murphy et al. found additional Peter Pan disks in the literature, which were identified as part of GAYA (Great Austral Young Association, containing Carina, Columba, Tucana-Horologium[8]) complex.[4] Examples are 2MASS J0041353-562112 in Tuc-Hor,[9][10] 2MASS J05010082-4337102 in Columba and 2MASS J02265658-5327032 in Tuc-Hor.[11] The Tuc-Hor association has an age of 45±4 Myr and the Columba association has an age of 42+6
−4 Myr. 2MASS J0041353-562112 was later discarded as it does not show excess and could belong to the Beta Pictoris moving group.[2]

The Disk Detective Collaboration identified two additional Peter Pan disks: WISEAJ044634.16-262756.1 in Columba and WISEA J094900.65-713803.1 in Carina. Both systems are visual doubles. The paper also mentions that members of NGC 2547 were previously identified to have 22 μm excess and could be similar to Peter Pan disks.[2][12] 2MASS 08093547-4913033, which is one of the M-dwarfs with a debris disk in NGC 2547 was observed with the Spitzer Infrared Spectrograph. In this system the first detection of silicate was made from a debris disk around an M-type star. While the system shows the H-alpha line, it was interpreted to be devoid of gas and nonaccreting.[13]

Implications for planet formation around M-stars

There are different models to explain the existence of Peter Pan disks, such as disrupted planetesimals[4] or recent collisions of planetary bodies.[6] One explanation is that Peter Pan disks are long-lived primordial disks[14] . This would follow the trend of lower-mass stars requiring more time to dissipate their disks. Exoplanets around M-stars would have more time to form, significantly affecting the atmospheres on these planets.[1][2]

gollark: Well, the actual emitter bit would.
gollark: Well, strictly speaking, they don't have a temperature.
gollark: So, basically a nicoll-dyson beam?
gollark: Then make the arms out of muon metal. That couldn't go wrong.
gollark: Those, you see, are cool.

See also

References
  1. silverbergastro (2020-01-17). "Our New Paper: "Peter Pan Disks"!". Disk Detective. Retrieved 2020-01-22.
  2. Silverberg, Steven M.; Wisniewski, John P.; Kuchner, Marc J.; Lawson, Kellen D.; Bans, Alissa S.; Debes, John H.; Biggs, Joseph R.; Bosch, Milton K. D.; Doll, Katharina; Luca, Hugo A. Durantini; Enachioaie, Alexandru; Hamilton, Joshua; Holden, Jonathan; Hyogo, Michiharu; the Disk Detective Collaboration (2020-01-14). "Peter Pan Disks: Long-lived Accretion Disks Around Young M Stars". arXiv:2001.05030 [astro-ph.SR].
  3. Silverberg, Steven M.; Kuchner, Marc J.; Wisniewski, John P.; Gagné, Jonathan; Bans, Alissa S.; Bhattacharjee, Shambo; Currie, Thayne R.; Debes, John R.; Biggs, Joseph R. (14 October 2016). "A New M Dwarf Debris Disk Candidate in a Young Moving Group Discovered with Disk Detective". The Astrophysical Journal. 830 (2): L28. arXiv:1610.05293. doi:10.3847/2041-8205/830/2/L28. ISSN 2041-8205.
  4. Murphy, Simon J.; Mamajek, Eric E.; Bell, Cameron P. M. (2018-05-21). "WISE J080822.18−644357.3 – a 45 Myr-old accreting M dwarf hosting a primordial disc". Monthly Notices of the Royal Astronomical Society. 476 (3): 3290–3302. arXiv:1703.04544. Bibcode:2018MNRAS.476.3290M. doi:10.1093/mnras/sty471. ISSN 0035-8711.
  5. "Low-mass Stars | Steven M. Silverberg". www.nhn.ou.edu. Retrieved 2019-07-25.
  6. Flaherty, Kevin M.; Hughes, A. Meredith; Mamajek, Eric E.; Murphy, Simon J. (2019-02-13). "The Planet Formation Potential Around a 45 Myr old Accreting M Dwarf". The Astrophysical Journal. 872 (1): 92. arXiv:1812.04124. Bibcode:2019ApJ...872...92F. doi:10.3847/1538-4357/aaf794. ISSN 1538-4357.
  7. Ramsey, Sarah (2016-10-21). "Citizen Scientists Discover Potential New Exoplanet Hunting Ground". NASA. Retrieved 2020-01-22.
  8. Torres, C.A.O.; Quast, G.R.; Melo, C.H.F.; Sterzik, M.F. (2008). "Young Nearby Loose Associations - aspmonographs.org". arXiv:0808.3362 [astro-ph].
  9. Reiners, Ansgar (21 August 2009). "Evidence for Accretion in a Nearby, Young Brown Dwarf". The Astrophysical Journal. 702 (2): L119–L123. arXiv:0908.3482. Bibcode:2009ApJ...702L.119R. doi:10.1088/0004-637X/702/2/L119. ISSN 1538-4357.
  10. Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne (24 February 2014). "Banyan. Ii. Very Low Mass and Substellar Candidate Members to Nearby, Young Kinematic Groups with Previously Known Signs of Youth". The Astrophysical Journal. 783 (2): 121. arXiv:1312.5864. Bibcode:2014ApJ...783..121G. doi:10.1088/0004-637X/783/2/121. ISSN 0004-637X.
  11. Boucher, Anne; Lafrenière, David; Gagné, Jonathan; Malo, Lison; Faherty, Jacqueline K.; Doyon, René; Chen, Christine H. (15 November 2016). "Banyan. Viii. New Low-Mass Stars and Brown Dwarfs with Candidate Circumstellar Disks". The Astrophysical Journal. 832 (1): 50. arXiv:1608.08259. Bibcode:2016ApJ...832...50B. doi:10.3847/0004-637X/832/1/50. ISSN 0004-637X.
  12. Forbrich, Jan; Lada, Charles J.; Muench, August A.; Teixeira, Paula S. (November 2008). "New M Dwarf Debris Disk Candidates in NGC 2547". The Astrophysical Journal. 687 (2): 1107. arXiv:0807.3597. Bibcode:2008ApJ...687.1107F. doi:10.1086/592035. ISSN 0004-637X.
  13. Teixeira, Paula S.; Lada, Charles J.; Wood, Kenneth; Robitaille, Thomas P.; Luhman, Kevin L. (July 2009). "Infrared Spectrograph Characterization of a Debris Disk Around an M-Type Star in NGC 2547". The Astrophysical Journal. 700 (1): 454–459. arXiv:0905.2469. Bibcode:2009ApJ...700..454T. doi:10.1088/0004-637X/700/1/454. ISSN 0004-637X.
  14. Coleman, Gavin; Haworth, Thomas J. (June 2020). "Peter Pan discs: finding Neverland's parameters". Monthly Notices of the Royal Astronomical Society. 496 (1): 111. arXiv:2006.06115. Bibcode:2020MNRAS.496L.111C. doi:10.1093/mnrasl/slaa098.
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